ONe of the ideas you sometimes heard wistfully is that the addition of America to the British Empire (or rather not losing it in the Revolution) would have made Britain into a global hegemon even above and beyond OTL.
But did the loss of America really hurt Britain? Even after independence, Britain continued to trade and invest in America; the two pursued complementary foreign policy goals for much of the 19th and 20th century.
It seems as if even if the Revolution was aborted, nothing much would have changed in terms of British power.